Drill hole slope indicator



' Feb. 25, 1958 N. A. NELSON DRILL HOLE SLOPE: INDICATOR 2 Sheefs-Sheet 1 Filed July v1, 1954 IAG/T..

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Feb. 25,y 1958 Filed July 1,. 1954 N. A. NELSON DRILL HOLE SLOPE INDICATOR 2shets-sheet 2 INVENTOR. Norman A. Ale/son,

BY www@ gram/Ex Vthrough the medium of a rotary table.

drawings.

United States Paten-t O a 2,824,380 yDRM. HOLE SLOPE INDICATOR Norman A. Nelson, Genoa, Tex., assignor, by mesne assignments, to Esso Research and Engineering Company, Elizabeth, N. J., v:incorporation of Delaware .Application July 1, 1954, Serial No;.440,733

l4ciai1ms. (Graaf-20s) This invention relates to the art of: drilling boreholes .into-subsurface formations by the rotar-ydrillingvmethod and, more particularly, relates to the art of detecting,

Vascertainingand indicating deviations fromfvertical of a ,borehole drilled by said method. Y

In thedrilling-of boreholes byftherotar-y drilling method, the equipment employed includes awdrill-fbit which `annular space between :the drill pipeV and the borehole ADuring the drilling of the borehole by .the rotary drilling m'ethod,.it-is.often difficult to maintaina vertical course. Because deviations from -the vertical, if of any .appreciable magnitude, cause many diiculties, it hasbeen the ,practice ,to survey the borehole rfrom timeto time Ito determine whether or notthe boreholeis deviating from the vertical and to-determine the extent of thedeviation, if any.

Many different devices have ybeen lsuggested for use for the aforementioned purpose `although most of 4these devices have been'found to be impracticalrin one or more respects. Some of these kdevices are Lequipped witha valve which is adapted ytoclose :oit the central passage extending through the drill pipe for the making of a determination as kto theinclination ofV theborehole;

no -meansare provided for opening this valve after'thedetermination has been made and, accordingly, the drill Stem must Abe removed from the hole while it.stands.full

'of drillingV mud. yDisadvantages, which attend to` .such

a practice are i obvious.

`I`t is an object ofthe present invention to provide a ldevice radaptedto determine and to indicate vthe degree of, inclination of a borehole from the vertical. ,further object of the vpresent invention to provide such a Vdevice equippedwith valve means which can be .locked in Athe open position to permit the pulling of a dry drill .v

string.

The aforementioned objects and other advantages of .my invention will be .apparent from the followingdetailed description taken in conjunction with the accompanying ln the `drawings like numerals indicate like. parts throughout. f f

Fig. `1 is a view vin partial elevation of the device of L-the"present 'invention whennormal circulation of drilling tiuidis maintained and the device is held in an open posi- Fig. 2 ina viewsimilar to that of Fig. l but`with. circulation of drilling liuid stopped and the device assuming ya yclosed position;

A Eig. 3 is a detailed sectional view ot thedevice shown toa drill bit, not fshown.

2,824,380 Patented Feb. 25, 1958 ice in Figs. l and 2, but with the device locked in v`anopen position byA a retrievablego-devil;

Fig. 4 is a sectional view of the lower portion of the device shown in Fig. 3;

Fig. 5 is a sectional view taken along the `line 5-5 ofFig. 3;

.-Fig. 7 is an enlarged detail view of a portion of't Ve 'device shown in Fig. 4.

Referring tothe drawing, numeral .10 designates a .section of drill string and 'preferably` is a drill collar sub.`

An inwardly projecting shoulder 11 is providedww'ith drill pipe 10'preferably a short distanceabove' the lowerv end Aof the-drill vstem atthepoint at'whichit'is-attached The device of my invention is lshownin Fig. l as it`would normally be positioned within a drillfpipe 10.

The device of'my invention includes a housing 12, preferably tubular, as shown, which may be formed 'offa series of sections joined by screw threads as at 13. Aixed `to the upper extremity of 'housing' 12 is a spear 14 to which maybe attached a-wire line, not shown, -for lower- 'ingorraisingthedevice in drill pipe 10. Housing 12 adjacent its upper end' defines a closed chamber 15 with a pendulum 16 suitably suspended fromfthe upper end thereof. So that pendulum 16 may readily attain a vertical position at all times,l upper bearing 17 and lower bearing 1 8Yare provided and held in place against pendulum 16 by means of locking ring 1-9. Alsoposivtioned Within chamber 15 is a detector piston 20 defining ystep-wise recess 21 in its upper surface. Step-wise recess 21 in reality consists of a series ofconcentri'c recesses of decreasing diameter designatedvas 21a, 2lb,- 21e, and

21dforming a series of ledges ydesignated by'numerals 21e, 21j, 2lg,.21h, and.21.

Thelower end vof chamber 15 is closed by means of packing glandZZfdeningtopening .23 extending vertically therethrough. Opening-23 is provided with an annular groove 24fadapted-to receive sealing means, such asan O-ring24..` f

Housing i2 also defines a second chamber,'thisrchamber being designated by the numeral 25. Mounted within housing 12 and forming the upper end yofvchamberA 25 is Vpiston 26 carrying sealing ring270n its vouter periphery, piston l26 being adapted to be moved longitudinally'with- .inhousing 12 in fluid-tightirelation vwith the' walls thereof.

Partition 28 constitutes the-lower wall .ofvchamberiz Extending vertically through partition 28A are three/sep- .arate openingsadesignated by the numerals-29,1 30,` and 31 and shown Vin greater detail in-Fig. 7. The passage of fluid downwardlythrough opening 29 is prevented by oneway or uni-directional flow valve 32 consisting of 'a'ball 3 3 biased downwardly against the valve seat by spring/34. Opening 31 isclosed by means of -a frangible disc 37 held in place by retaining nut 38. Screw-threaded into-open- -ing 30 is orifice plate-36 yprovided -with'bidirectional'tlow orice 36.

Frangible disc 37 is provided as a safety -feature so that iforilice 36 should become Aplugged,-discf37 will rupture, permitting vlluid to escape from chamber-,25. The size-of-orice4 is related to the dimensions of stepwise piston 20 in acmanner which will be described hereinafter. v 1

Spaced beneath partition 28L and screwthreaded :to housingklZ isplug 39 deliningvcentral" passage 7l0 yextend- -ing vertically therethrough. Attached to `plug 39'; asfgat A141,1is .a I'distensible,resilient bag 42which may suitably .'.be'nra'de of rubber. t

All'ixedk tofhousing 12. above its lower end by meat'rsi-"tif brackets 44 isa--sealing"member-43. On its louter cylinabbasso lower edge 46 of sealing member 43 is adapted to abut upon shoulder 11 carried by drill pipe 10 in which event sealing means 45 provides a fluid-tight seal between member 43 and drill pipe 10. t g

Mounted at the bottom 12fof housing 12 is sleeve valve S4, which is adapted to move slidably on the exterior of housing 12 in fluid-tight relation therewith as a result of vthe seal provided by sealing member 53 which may suitably be an O-ring. The outer dimension of sleeve valve 54 is such that it just passes thru the inside of sealing member 43, the outer surface of sleeve valve 54 and the inner surface of member 43 being adapted to cooperate to prevent or to retard materially the passage of fluid therebetween; in other words, a fluid-tight seal here is not essential. A nesting cage 54' for valve 54 may be provided.

Aflxed to the upper end of slide valve 54 is a valve actuating member which may suitably be a plurality of rods 60 extending upwardly along housing 12 and freely past the centering7 fins 62. Rods 60 terminate above centering fin 62 and they may be connected as by means of a ring 63. Rods 60 are connected by means of a yoke 64 to piston rod 26', screw 65 securing yoke 64 to piston rod 26'.

Step piston and piston 26 are connected together for movement in concert by means of piston rod 26', piston rod 26 extending through opening 23 of packing gland 22 in fluid-tight relation therewith, sealing means 24' providing the seal.

It will be noted that the lower end 12' of housing 12 is open so that the exterior surface of resilient bag 42 is exposed to the drilling fluid which fills the central opening of drill pipe 10. It is also essential that the upper surface 26a of piston 26 be exposed to the fluid inside drill pipe 10. In the device shown in Fig. 1 access by the drilling uid is had to the upper surface 26a of piston 26 through slot 70 in housing 12. This arrangement is essential so that there is a pressure differential between the upper surface 26a of piston 26 and the exterior surface of bag 42. It is also essential that a biasing means, such as spring 72` be provided for biasing piston 26 upwardly within housing 12. the bias exerted by the biasing means being less than the pressure differential between the drilling uid adjacent the upper surface 26a and the drilling fluid surrounding bag 42.

In the drawing the space between wall 28 and plug 39 is shown as being connected with the space between the packing gland 22 and step piston 26 by means of a conduit 75. This conduit or similar connection is not essential and may be omitted entirely. If, however, a conduit such as conduit 75 is provided, step piston 20 is then provided with a passage 76 which connects the space between step piston 20 and packing gland 22 with recess 21 of piston 20. If a conduit 75 is provided, chambers 15 and 25 are both filled with a hydraulic fluid, conduit 75 permitting the fluid pressure in each of these chambers to be equalized. Filling of these chambers is accomplished by removing plug 9 in the upper part of chamber 15. Irrespective of whether chamber 15 is filled with uid and fluidly connected with chamber by means of conduit 75, chamber 25 and bag 42, together with the interconnecting spaces, are filled with uid. Filling should be accomplished when piston 26 is in its uppermost position and when bag 42 is in its undistended state.

In use the device of my invention operates in the manner hereinafter described.

After the drill bit attached to the lower end of drill pipe 10 has been placed on bottom, the device of my invention is inserted in drill pipe 10 at the surface of the earth and pumped downwardly therein until shoulder 46 of sealing member 43 abuts on shoulder 11 of drill pipe 10. While drilling fluid is being circulated downwardly within drill pipe 10 and upwardly throughthe annular space between drill pipe 10 and the walls of the borehole, the pressure differential between bag 42 and upper surface 26a of piston 26 as a result of circulating fluid forces piston 26 to its lowermost position as is best illustrated in Fig. 4. Inasmuch as slide valve 54 is mechanically connected to piston 26 through rods 60, yoke 64, and piston rod 26', slide valve 54 is also in the full down position. Piston 26 and slide valve 54 remain in the full down position so long as circulation is continued.

When circulation of drilling uid is discontinued and there is no differential pressure across this device, spring 72 is the only effective unbalanced force operating on the device of my invention and causes piston 26 to move upwardly and slide valve 54 to move into the central opening in sealing member 43. If the borehole does not deviate from the vertical, the detector step piston 20 will move upwardly within chamber 15 until the lower end of pendulum 16 strikes the bottom of recess 2li, thus preventing further upward movement of step piston 20 and and piston 26. If however, the borehole is inclined from the vertical. the lower end of pendulum 16 will strike on ledge 21e, 21f, 21g, or 21h of recess 21, the particular ledge involved depending upon the degree of departure of the borehole from the vertical. Of course, the amount by which piston 26 is permitted to move will depend upon the particular ledge upon which the lower end of pendulum 16 abuts.

The operator can determine which of the aforementioned ledges the lower end of pendulum 16 has abutted upon by applying to the drilling mud within drill pipe 10 a predetermined pressure and then promptly shutting off the pumps by which this pressure was attained. This pump pressure acts on the upper surface 26a of piston 26 forcing piston 26 downwardly within chamber 25. The rate at which piston 26 moves downwardly is deterlmined by the rate at which fluid can be displaced from chamber 25 into resilient bag 42 through orifice 36'.

The size of orifice 36 has been preselected so that the time required to displace fluid from chamber 25 into bag 42 is inversely proportional to the slope of the borehole. The time which the operator would measure for determining the slope of the borehole would be the period from the initial pump pressure built up until the pump pressure drops off suddenly.

Check valve 32 is provided in order that orifice 36 may be by-passed when piston 26 is moving upwardly so that chamber 25 can be filled quickly and easily. Frangible disc 37 is provided as a safety feature in the event that orifice 36' should become plugged, the frangible disc being rupturable by applying pump pressure to lthe drilling fluid inside drill string 10.

Prior to removing drill string 10 from the borehole, a go-devil 100, shown in Fig. 3, is introduced into the hole for locking slide valve 54 in the open position so that drilling` fluid can drain out the lower end of drill string 10 and the string removed dry from the hole. Go-devil is provided at its upper end with a spear 101 and a downwardly depending skirt 102. It is also provided with a plurality of latching dogs 103 normally pressed downwardly and inwardly by a biasing means, such as spring 104. The lower edge 105 of skirt 102 is arranged to contact ring 63, pushing said ring and the rods 60 attached thereto downwardly. Inasmuch as rods 60 are attached to slide valve 54, slide valve 54 is also held in the full down open position so that drilling uid located thereabove can ow therepast and out the lower end of the drill string. Springs 104 bias dogs 103 inwardly so that the upper edge 106 of these dogs engages with the lower edge 14' of spear 14 when godevil 100 is raised. It will be understood, of course, that go-devil 100 may be raised by means of a wireline attached to spear 101.

It will be appreciated that various changes may be made in the device of my invention without departing from the fspirit thereof.

What I wish to claim as new and novel and to secure by Letters Patent is:

l. A borehole slope indicator for use in a tubular member positioned in said borehole, comprising, in combination, a housing including a first closed chamber and a second chamber; a pendulum suspended in the upper end of said closed chamber so as to hang vertically at all times; a piston in said closed chamber arranged for longitudinal movement in said chamber having a stepwise recess in its upper surface capable of receiving the lower end of said pendulum; a piston in said second chamber arranged for longitudinal movement in said chamber in sealing contact with the walls forming said chamber, the upper surface of said piston being exposed to fluids surrounding said housing; a spring biasing upwardly the piston in said second chamber; a piston rod connecting the piston in said first closed chamber with the piston in said second chamber, said piston rod being adapted to pass in and out of said llrst closed chamber in fluidtight relation, with the walls forming said chamber; a sealing member affixed to said housing and adapted to fit sealably in said tubular member, said sealing member defining flow space therethrough; a valve element mounted on the lower end of said housing mechanically connected to said pistons for simultaneous movement therewith, said valve element being adapted to move in and out of the flow space through said sealing member for opening and closing completely said llow space to the passage of fluid therethrough upon each downward and upward movement, respectively, of said pistons; and a distensible reservoir defining an enclosed chamber in fluid communication through stationary openings of selected size with said second chamber, the outer surface of said distensible reservoir being exposed to the fluid located below said sealing member in said tubular member.

2. A borehole slope indicator for use in a drill pipe through which drilling fluid may be circulated under pressure comprising, in combination, a housing defining a first chamber vertically spaced above and longitudinally aligned with a second chamber; a pendulum suspended adjacent the closed upper end of said first chamber; a first piston arranged for longitudinal movement in said first chamber having a recess in its upper surface consisting of a series of concentric circular ledges, the diameter of which decreases as the depth of the recess increases; a second piston arranged for longitudinal movement in said second chamber in sealing tight relation with the walls of the housing forming said chamber, the upper surface of said second piston being exposed to said drilling fluid; a spring biasing said second piston upwardly in said second chamber; a piston rod connecting together said first and second pistons, said piston rod being adapted to pass in and out of said first chamber in fluid-tight relation with the housing forming said chamber; a sealing member aixed to said housing and adapted to be positioned within said drill pipe in fluid-tight relation therewith, said member defining a flow space'extending vertically therethrough; a sleeve valve mounted on the lower end of said housing below said sealing member, said sleeve valve being adapted to be moved longitudinally on said housing in fluid-tight relation therewith for opening and closing the flow space through said sealing member; a valve actuating member affixed to said valve and extending along said housing to a point adjacent the upper end thereof, said actuating member also being affixed to said piston rod for movement in unison with said rod; a distensible, resilient bag defining an enclosed chamber in fluid communication through an orifice with said second chamber, the outer surface of said bag being exposed to the drilling fluid located below the contact area between said sleeve valve and said sealing member.

3. A device as defined in claim 1 wherein said stationary openings comprise a bi-directional flow orifice, a uni-directional flow valve orifice and a normally closed frangible safety orifice.

4. A borehole slope indicator for use in a well pipe comprising a longitudinally extending housing positioned in said pipe, a pendulum suspended in said housing adapted to assume a vertical position, longitudinally movable detector means arranged in said housing adapted to be moved downwardly by the action of circulating fluid, means connected to said detector means adapted to urge said detector means upwardly, the upward movement of said detector means being limited by said pendulum, a sealing member arranged on said housing in fluid-tight relation to said pipe, said member defining a flow space extending vertically therethrough, a valve element mounted on the lower end of said housing in fluid-tight engagement therewith and connected to said detector means for longitudinal movement therewith, said valve element opening and closing completely the flow space through said sealing member upon each downward and upward movement, respectively, of said detector means, stationary bi-directional fluid flow control means arranged in said housing adapted to control downward movement of said detector means in order to determine deviations of the borehole from the vertical, and distensible means, the interior thereof fluidly communicating with said fluid flow control means and the outer surface thereof being exposed to fluid located in said pipe.

References Cited in the file of this patent UNITED STATES PATENTS 2,046,956 Lynch July 7, 1936 2,329,732 Varney et al. Sept. 2l, 1943 2,482,224 Swearingen Sept. 20, 1949 2,762,132 Varney Sept. 11, 1956 

